(9-22) Epidemiology (Yay!) Flashcards
1. Explain the importance of John Snow’s work in nineteenth century London. 2. Define epidemiology 3. Define the following: Portal of exit, Portal of entry 4. Define and differentiate between morbidity rate and mortality rate. 5. Define and differentiate between incidence and prevalence. 6. Define: Endemic, Epidemic, Pandemic 7. Define reservoir and give examples. 8. Differentiate between symptomatic infection and asymptomatic carriers. 9. Define zoonoses. 10. Differentiate between hori
Define: Rate
Rate is the percentage of a given population that is infected.
Define: Attack Rate
Attack Rate is the number of cases developing in group of people exposed.
How is Morbidity rate calculated?
Morbidity rate = number of cases of illness divided by the population at risk.
What does the Mortality rate reflect?
Mortality rate reflects population that dies from disease.
What does Incidence reflect?
Incidence reflects number of new cases per specific time period.
What is Prevalance?
Prevalence reflects total number of existing cases.
What is an epidemic?
Unusually large number of cases in a population constitutes an epidemic.
When epidemics spread worldwide they are termed what?
Pandemics
What is a pathogen’s Portal of Entry?
Route by which pathogen enters body.
List 6 major portals of entry.
- Eyes
- Ears
- Respiratory tract
- Broken skin
- Digestive tract
- Genitourinary tract
Can disease severity vary based on portal of entry? Elaborate on Yersinia pestis as an example.
Yes.
~ Yersinia pestis entry into blood termed bubonic plague: Noncontagious, 50-75% mortality
~ Yersinia pestis entry into lungs termed pneumonic plague: Highly Contagious, <100% mortality
What is vertical transmission of an infectious disease?
Transfer of pathogen from mother to fetus
Why is a Portal of Exit necessary?
Microbes must leave one host in order to be transmitted to another host.
How are organisms inhabiting the intestinal tract shed?
Organisms inhabiting intestinal tract are shed in feces, sometimes in copious amounts of watery diarrhea.
~ ex. Cholera
How are Organisms inhabiting the respiratory tract expelled?
Organisms inhabiting respiratory tract are expelled in respiratory droplets of saliva.
~ ex. B. pertussis
How are organisms of the skin shed?
Organisms of the skin are shed with skin cells as they slough off.
What are the 2 basic types of transmission of infectious diseases?
- Vertical
- Horozontal
What are teh 3 types of horizontal transmission of an infectious disease?
- Vehicle transmission – a medium such as air, food, or water
- Contact transmission – direct/indirect contact & droplets
- Vectors – Animals that carry pathogens from one host to another
What 2 types of mechanical transmission do vectors use to spread disease?
- Mechanical transmission – passive transport on feet or body parts
- Biological transmission – more complex active process
Which 3 vector routes can pathogens be transmitted by?
[Hint: “elemental”]
- Food
- Water
- Air
What are the 2 ways that food can become contaminated?
- Microorganisms can originate with animal
~ ex. Salmonella naturally lives on poultry - Organisms can be inadvertently added during food preparation
~ ex. Staphylcoccus aureus from improperly washed hands or Salmonella from cross-contamination of cutting boards or knives
What can water be contaminated by?
Feces
Why can waterborne disease outbreaks involve large numbers of people?
Municipal water is distributed to large areas.
Small Respiratory droplets can be transmitted via what?
The air. Smaller droplets can remain suspended indefinitely in presence of light air currents.
How can vehicular transmission of pathogens through food, water, and air be prevented?
- Food: Sound food-handling methods
- Water: Chlorination and filtration
- Air: HEPA filters
Which 2 types of living agents can pathogens can be transmitted through?
- Humans
- Non-human vectors
What are the 3 ways that humans spread disease in a vector-like way?
- Direct contact
- Indirect contact
- Droplet transmission
What are 2 ways that humans spread disease through direct contact, and how can each way be prevented?
- Hands
~ Prevention: Hand washing - Sexual contact
~ Prevention: Condoms or absenence
What are fomites?
Inanimate objects that aid in human disease transmission via indirect contact.
What is the preventative measure for diseases that involve indirect contact through fomites?
Handwashing
How can pathogens be spread via droplet transmission?
Microbe-laden respiratory droplets can be inhaled by people within close proximity.
What is the most common non-human disease vector?
Arthropods– mostly insects, but can also be arachnids.
Give 2 examples of disease vectors that carry organisms internally.
- Tick
- Mosquito
Give an example of a disease vector that carries organisms externally.
Flies
How can vector-borne diseases be controlled?
By controlling the arthropod population.
Define Reservoirs of Infectious Diseases.
A reservoir is the natural habitat of a pathogen.
Which 3 ways can reservoirs be classified?
- Human
- Non-human animal
- Environmental
What are the most significant reservoirs of communicable diseases?
Infected humans
Human reservoirs can serve which 2 functions?
- Symptomatic infections
- Asymptomatic carriers (subclinical or inapparent)
What is the term for an individual who harbors pathogen with no ill effects?
Asymptomatic carriers (subclinical or inapparent)
What is the term for a disease transmitted by non-human animal reservoirs?
zoonotic
The pathogens that are more difficult or nearly impossible to eliminate have which class of reservoir?
Environmental
What is a synonym for Nosocomial Infections?
Hospital-acquired infections
What are the state, national, and world levels of Infectious Disease Surveillance?
- State: State Public Health Departments
- National: Centers for Disease Control and Prevention (CDC)
- World: World Health Organization (WHO)
What are State Public Health Departments responsible for?
Infection surveillance and control
Who publishes data in weekly publication - Morbidity and Mortality Weekly Report (MMWR)?
The Centers for Disease Control and Prevention (CDC)
What 4 tasks does the World Health Organization (WHO) perform?
[G.S.P.T.]
- Provide worldwide GUIDANCE in the field of health
- Set global STANDARDS for health
- Cooperatively strengthen national health PROGRAMS.
- Develop and transfer appropriate health TECHNOLOGY.
What 3 tasks do the Centers for Disease Control and Prevention (CDC) perform?
[D.C.P.]
- Can DISPATCH teams worldwide to assist in identification and control of epidemics
- COLLECTS data of public health importance
- PUBLISHES data in weekly publication - Morbidity and Mortality Weekly Report (MMWR
What 4 activities have contributed to the reduction and eradication of disease?
- Hand washing
- Improving sanitation
- Reservoir and vector control
- Vaccination
in what 2 ways do diseases emerge?
- New diseases emerge
- Old controlled diseases make a comeback
